As is generally quite well known in the railway coupling art, there are a number of different designs for slackless type drawbar assemblies that are in rather widespread service in the railroad industry at the present time. Essentially, each of the different railway car coupler manufacturers has its own particular design for a slackless drawbar assembly that it normally supplies to such railroad industry. Each of such different slackless type drawbar assemblies is utilized to connect the adjacently disposed ends of a pair of freight cars together in a substantially semipermanent manner.
In particular, these slackless type drawbar assemblies, which are in use at the present time, have generally provided the railroad industry with a more modern style freight car coupling arrangement. These slackless drawbar assemblies have substantially eliminated the need for a relatively expensive draft gear assembly as well as other freight car coupling components that were normally required before the introduction of such slackless type drawbar assemblies.
Furthermore, these slackless drawbar assemblies have generally resulted in an overall net decrease in the empty weight of such freight cars. This overall net weight reduction of such freight car is an extremely important factor to be taken into consideration by the user of such railway freight car in view of the ever rising energy cost.
It is believed to be equally well recognized, in the railroad industry, that these slackless drawbar assemblies are primarily installed on a freight car which will be utilized in a dedicated service type of application. Most of the freight cars that are primarily utilized in this dedicated type service normally will not require that they be uncoupled except for routine maintenance and/or possible repair.
By way of example only, such freight cars which generally are used in such dedicated type service will at least include: coal cars, automobile and light truck transport cars and certain tank cars.
Each of such slackless drawbar assemblies which are known to be in use at the present time, however, suffer from at least one important and common disadvantage. This common disadvantage is that these slackless drawbar assemblies all require a significant number of component parts.
Additionally, many of these component parts include a number of certain selected surfaces thereof that are frictionally engaged and are subjected to extremely high loads during in-track service. Furthermore, such frictionally engaged surfaces are periodically required to move relative to one another while under such extremely high loads.
It should be obvious, particularly to persons who are skilled in the relevant mechanical arts, that such relative movement between these frictionally engaged surfaces, particularly when they are in a loaded condition, will quite often result in not only the generation of considerable heat, but also substantial wear of these component parts thereby resulting in relatively frequent and rather costly maintenance having to be carried out. In some of the more severe cases, these freight cars must even be removed from a revenue generating type service for relatively long periods of time.
These slackless type drawbar assemblies have, nevertheless, gained a rather widespread acceptance in the railroad industry over the past several years in spite of the number of disadvantages which were discussed in some detail above. This would be expected, however, because there are a number of significant advantages that were gained by such railroad industry, over the older style standard type coupling arrangements which were and still are being used. Experience has demonstrated that these advantages far outweigh the disadvantages and such slackless drawbar assemblies have proven to the railroad industry over an extended period of time to be quite cost effective.